Itchy skin is the most common symptom in dermatology clinics, and its causes are very complex and can be divided into the following categories: 1. skin allergies: such as urticaria, dermatitis, eczema, drug allergies; 2. skin infections: such as ringworm, ringworm, scabies; 3. neuropsychiatric factors: such as neurodermatitis, itchy rash; 4. visceral diseases: such as diabetes, thyroid insufficiency, hyperthyroidism, liver and gallbladder diseases, renal insufficiency, tumors; 5. other conditions: dry weather, high temperature, etc.